Linux Distributions Compared

Back in March, we compared the available Linux distributions. This review draws heavily from that work and offers updated infromations on what is available on PC platforms.

A Linux distribution is a package that
contains the Linux kernel, application and utility programs and an
installation method. While all distributions are based on the same
or similar kernels and many of the same utilities, each
distribution has something different to offer the consumer. Thus,
while there really isn't a best distribution,
there are distributions that are better for different users. In
this article, we attempt to offer you enough information so you can
select the distribution best for you.

Is this a cop-out? Are we shirking our duty? It has become
clear to us that it would be hard for Linux Journal to rank the distributions; our staff members
have different personal favorite distributions and defend their
choices rationally—occasionally even argumentatively. At
Linux Journal, we use Linux
extensively—nearly exclusively—and we still don't agree which
distribution is the best. We have different priorities, skills, and
expectations, and we believe this is true of our readers as
well.

Before we get too deep into this review, note that as this is
being written, the Linux 2.0 kernel is about to be released (the
scheduled release date is June 9, 1996). This new kernel offers
some major enhancements. (See the interview with Linus in this
issue for details.) The distributions will surely be updated to
take advantage of this new kernel. Look for an updated review in
the special Buyer's Guide issue of Linux Journal, which will be out in February 1997.

Some of the descriptive text that originally appeared in the
March 1996 review article has been removed. If you want to look at
all the information presented in that issue, it is available on our
web site,
/issue/0023.

Version Numbers

Many new Linux users confuse the version of the
distribution they are using with
the version number of the kernel.
As mentioned above, the Linux kernel is just one of the many pieces
of software needed to create an entire distribution. Each
distribution uses version numbers of its own to keep track of the
state of the entire distribution, which has more to do with the
collection of programs than with the particular kernel involved.
Indeed, many distributions have included two or more different
kernel versions in one version of the distribution.

However, it's worth understanding the version numbers used
for the Linux kernel itself, since the kernel is a key part of any
Linux distribution. Kernel version numbers come in three parts: the
major version number, the
minor version number, and the
patch-level. The Linux kernel is
being constantly developed by a large team of developers, and while
they add new features, they occasionally introduce new bugs. To
keep this from causing a problem for Linux users, the developers
periodically dedicate several months to fixing bugs and creating a
very robust, stable kernel. When this is done, a
stable version is released with an
even-numbered minor version
number. The developers then begin adding features (and temporarily
breaking things sometimes) to development
versions with
odd-numbered minor version
numbers.

Unless you want to live on the “bleeding edge” of Linux
development, you will probably want to stick with the latest stable
kernel version. As of this writing, the latest stable kernel
version is 2.0, but most distributions are based on the previous
production kernel, which is 1.2.13.

One of the most common sources of confusion in the Linux
world today involves binary file formats (See
What is a binary file format?).
Most vendors have now switched from the older “a.out” binary file
format to the new “ELF” binary file format.

ELF is the binary file format used by Unix System V Release
4, but that doesn't mean a Linux binary in the ELF file format is
compatible with SVR4, nor does it mean that SVR4 binaries can run
on Linux. The capability for Linux to run
some SVR3 and SVR4 binaries is
provided by the BCS2 compatibility
package, which most distributions include.

One of ELF's features is extensibility; with ELF, it is
possible for developers to add features that weren't thought of
when the format was first designed. For instance, one Linux
developer has noted that he could add icons to ELF executables
without breaking any software. Icons weren't considered when ELF
was developed, but the format is extensible enough that they can be
easily added.

But perhaps you don't care if you can add an icon to your ELF
binary, or even if anyone else can. What does ELF do for you?
Fundamentally, it makes life much easier for Linux developers. It
also has a few esoteric features which make it practical to support
some software under Linux that was previously impractical to
support. So it gives you more and better software available for
Linux.

What do we mean by
based?

ELF-based means the entire distribution or, at least, almost
the entire distribution, consists of ELF binaries. Binaries in the
a.out format are not provided with the system, or if they are
provided, they either aren't part of the “core” of the system or
they are not available in ELF format.

By contrast, “supports ELF” means that, while the
distribution is partially or completely built of binaries in the
a.out format, the ELF programming
libraries are included so that ELF binaries will also
run.

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